Light hardenable or light curable materials are widely used in dentistry for the restoration of teeth. Many of such materials are made to provide optical characteristics that resemble those of natural teeth. Further such materials typically can be placed precisely and conveniently, can be hardened instantly, and the hardened material is typically relatively durable. Accordingly these materials are favored alternatives to less pleasant looking and over time self-hardening materials, like for example amalgam.
Light hardenable materials often include a polymerizable matrix material and filler materials including colorants, and may initially be generally soft or flowable so that they can be applied in a desired location and shape. For example, for restoration of a tooth the dental material may be filled into a tooth cavity and shaped so that the restored tooth resembles a natural tooth. Once the desired shape has been formed, the material may be cured by exposing it to light of a desired wavelength. The light typically activates photoinitiators in the dental material that cause the matrix material to polymerize.
The use of dental materials that are hardenable by blue light of a wavelength of between about 450 and 500 nm (nanometers) has become common in dentistry. Accordingly, light-emitting devices used for hardening such dental materials typically emit light at such wavelengths. Such a light-emitting device is for example available from 3M Deutschland GmbH, Germany, under the trade designation Elipar™ S10.
A variety of light devices have been developed or proposed. For example U.S. Pat. No. 5,147,204 discloses a light emitting apparatus for curing photocurable dental materials. The apparatus includes a handpiece having a housing, a depending handle and a detachable light guide. The light guide is received in a head connected to the housing. Rotational movement of the head relative to the housing also rotatably moves the light guide so that the guide may be turned by the same hand of the user that is grasping the handle. Additionally, a pivotal connection between the housing and the handle permits limited pivotal adjustment of the angle of the housing relative to the handle for improved manipulation and user comfort.
Because appropriate powerful, small and inexpensive light emitting diodes (LEDs) have become available over the past years, in some dental light hardening devices the light source has been placed directly in the intra-oral tip portion so that an elongated light guide for guiding light from the handle into the intra-oral tip could be eliminated.
For example US 2003/0147258 discloses a light curing device which includes a light source disposed at a distal end and a focusing means configured to focus light emitted from the light source. The light source is an LED light source and may include any quantity of LEDs. The focusing means includes lenses configured to collimate the light emitted from the light source.
Although there are a variety of light devices on the market there is still a desire to provide a device that is relatively convenient in handling. Further such a device is desirably inexpensive. There is also a desire to provide a device which can be used at a relatively high level of hygiene.